Microfabricated optical apparatus

ABSTRACT

A microfabricated optical apparatus that includes a light source driven by a waveform, a turning mirror, and a beam shaping element, wherein the waveform is delivered to the light source by at least one through silicon via.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. Patent Application is a Continuation based U.S. patentapplication Ser. No. 14/931,883, filed Nov. 4, 2015, which claimspriority to U.S. Provisional Patent Application Ser. No. 62/075,753filed Nov. 5, 2014. Each of these U.S. Patent Applications is herebyincorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

STATEMENT REGARDING MICROFICHE APPENDIX

Not applicable.

BACKGROUND

This invention relates to integrated circuit and microelectromechanicalsystems (MEMS) devices. More particularly, this invention relates to amicrofabricated optical apparatus wherein vias are formed completelythrough the silicon substrates.

Microelectromechanical systems (MEMS) are very small moveable structuresmade on a substrate using lithographic processing techniques, such asthose used to manufacture semiconductor devices. MEMS devices may bemoveable actuators, sensors, valves, pistons, or switches, for example,with characteristic dimensions of a few microns to hundreds of microns.One example of a MEMS device is a microfabricated cantilevered beam,which may be used to switch electrical signals. Because of its smallsize and fragile structure, the movable cantilever may be enclosed in acavity to protect it and to allow its operation in an evacuatedenvironment. Therefore, upon fabrication of the moveable structure on awafer, (device wafer) the device wafer may be mated with a lid wafer, inwhich depressions have been formed to allow clearance for the structureand its movement. To maintain the vacuum over the lifetime of thedevice, a getter material may also be enclosed in the device cavity uponsealing the lid wafer against the device wafer.

One such device that may be manufactured using MEMS techniques is anmicrofabricated optical table. Microfabricated optical tables mayinclude very small optical components which may be arranged on thesurface of a substrate in a manner analogous to a macroscopic opticalcomponents mounted on a full sized optical bench. These microfabricatedcomponents may include light sources such as light emitting diodes(LED's), beam shaping structures such as lenses and turning mirrors, andpolarization altering devices such as Faraday rotators and opticalisolators. After fabrication, these devices may be enclosed with a lidwafer to protect them in an encapsulated device cavity. Some devices,such as infrared detectors and emitters, may require a vacuum or lowmoisture environment, such that the device cavity may need to besubstantially hermetically sealed.

In order to control such a microfabricated elements, electrical accessmust be provided that allows power and signals to be transmitted to andfrom the elements. Previously, these signal lines were routed under thebond lines between the lid wafer and the device wafer. Because theenclosed elements may be delicate, the bondlines may be, for example,metal alloy bondlines that are activated at relatively low processingtemperatures. However, the presence of the flat metal bondlines directlyadjacent to potentially high frequency signal lines may cause unwantedcapacitance in the structure, limiting its high speed performance.

Accordingly, encapsulated microfabricated high frequency opticalstructures have posed an unresolved problem.

SUMMARY

A method is described which can be used to make microfabricated opticaltables using conductive vias which extend through the thickness of thesubstrate material.

A feature of this process is that conductive vias may be formed in arelatively insulative surrounding material of the substrate. These viasmay supply power and signals to/from the components inside asubstantially hermetically sealed device cavity. The signal and powerlines may be delivered to the sealed device cavity with a throughsubstrate via (TSV). The TSV may have a bonding pad on one side of thesubstrate, and a conductive line leading to the device within the devicecavity. Accordingly, this architecture avoids the large capacitivelosses that may occur with the under-bond routing of these electricalleads.

The encapsulated components may include turning mirrors, opticalrotators and isolators, light emitters and optical lenses. Using thisarchitecture, the turning mirror may be a reflective surface formed on asurface of the lid wafer, or it may be a separate component formed onthe device wafer surface.

Numerous devices can make use of the systems and methods disclosedherein. In particular, high speed, compact telephone or communicationsswitching equipment may make use of this architecture. RF switchesbenefit from the reduced capacitive coupling that an insulativesubstrate can provide. High density vias formed in the insulativesubstrate increase the density of devices which can be formed on asubstrate, thereby reducing cost to manufacture. Other sorts ofsubstrates, for example, metal or semiconducting substrates may make useof an insulating layer to provide isolation between the conductive viaand the surrounding substrate. The performance of such devices may alsobe improved, in terms of insertion loss, distortion and isolationfigures of merit.

Accordingly, the microfabricated optical apparatus fabricated on asubstrate, may include a light source driven by a signal, wherein thelight source generates optical radiation, a beam shaping element, and aturning surface which redirects the beam of light, wherein the signal isdelivered to the light source by at least one through silicon via (TSV)which extends through a thickness of the substrate. The systems andmethods may include elements of wafer level packaging (WLP), waferbonding, pick and place mechanisms, MEMS processes, methods, structuresand actuators.

The method for fabricating an optical apparatus on a substrate mayinclude forming a device cavity in a lid wafer, forming a throughsilicon via through the substrate, disposing a light source driven by awaveform which generates optical radiation on the substrate, andcoupling the light source electrically to the through silicon via,disposing a beam shaping element on the substrate, disposing a turningsurface which redirects the beam of light, and bonding the substrate tothe lid wafer to encapsulate the optical apparatus in a substantiallyhermetic device cavity.

These and other features and advantages are described in, or areapparent from, the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary details are described with reference to the followingfigures, wherein:

FIG. 1 is a schematic illustration of a prior art microfabricatedoptical apparatus;

FIG. 2 is a schematic, cross sectional illustration of a firstembodiment of a microfabricated optical apparatus;

FIG. 3 is a schematic, cross sectional illustration of a secondembodiment of a microfabricated optical apparatus;

FIG. 4 is a schematic, cross sectional illustration of a thirdembodiment of a microfabricated optical apparatus;

FIG. 5 is a schematic, cross sectional illustration of a fourthembodiment of a microfabricated optical apparatus;

FIG. 6 is a schematic, cross sectional illustration of a fifthembodiment of a microfabricated optical apparatus.

FIG. 7 is a schematic, cross sectional illustration of a sixthembodiment of a microfabricated optical apparatus with a plurality oflight sources; and

FIG. 8 is a plan view of a substrate with multiple optical apparatusesfabricated thereon.

DETAILED DESCRIPTION

The systems and methods described herein may be particularly applicableto microfabricated optical tables, wherein small optical devices areformed on a substrate surface and enclosed with a lid wafer. The opticaldevices may include light sources such as light emitting diodes (LED's),beam shaping structures such as lenses and turning mirrors, andpolarization altering devices such as Faraday rotators and opticalisolators. After fabrication, these devices may be enclosed with a lidwafer to protect them in an encapsulated device cavity. Some devices,such as optical detectors and optical or laser emitters, may require avacuum or low moisture environment, such that the device cavity may needto be substantially hermetically sealed. The signal and power lines maybe delivered to the sealed device cavity with a through substrate via(TSV). The TSV may have a bonding pad on one side of the substrate, anda conductive line leading to the device within the device cavity.

Through substrate vias may be particularly convenient for MEMS devices,because they may allow electrical access to the encapsulated devices.Without such through holes, electrical access to the MEMS device mayhave to be gained by electrical leads routed under the lid wafer whichis then substantially hermetically sealed. It may be problematic,however, to achieve a substantially hermetic seal over terrain thatincludes the electrical leads unless more complex and expensiveprocessing steps are employed. This approach also makes radio-frequencyapplications of the device limited, as electromagnetic coupling willoccur from the metallic bondline residing over the normally orientedleads. “Substantially hermetic” is used herein, should be understood toprovide a barrier against moisture penetration, and/or capable ofmaintaining vacuum to within about the 10 Torr range.

The systems and methods described herein may be particularly applicableto vacuum encapsulated optical tables, such as an LED, shaping lens,rotator/isolator and turning mirror, all enclosed in the device cavity.

The prior art is illustrated in FIG. 1, and exemplary embodiments of thenovel optical apparatuses are illustrated in FIGS. 2-8.

FIG. 1 shows a prior art example of an microfabricated optical table. Ascan be seen in FIG. 1, the output of laser light source 1 may be shapedby a ball lens 2 and then through Faraday rotator 3. A Faraday rotator 3s an optical device that rotates the polarization of light due to theFaraday effect, which in turn is based on a magnetooptic effect. TheFaraday rotator 3 in combination with a quarter wave plate outside thecavity, may provide optical isolation. The beam of light then impingeson a turning mirror 5 which redirects the light in a direction normal tothe substrate, shown downward in FIG. 1. The light may pass through thedevice substrate 7 on which the aforementioned devices are fabricated.In FIG. 1, the turning mirror is a discrete structure 5, encapsulated inthe device cavity along with the other components.

One of the problems with the device shown in FIG. 1 is that the leadsthat drive the laser emitter are necessarily routed under the bond linesthat bond the lid wafer 6 to the device wafer 7. Accordingly, a largecapacitive coupling may occur, with commensurately large lossesespecially at high frequencies. Although the device shown in FIG. 1 maybe smaller and lower cost than a TO-can packaging with ceramic carrier,the performance of the device may suffer from the aforementionedcapacitive coupling, especially at higher frequencies.

FIG. 2 shows a first embodiment of the systems and methods disclosedhere. In FIG. 2, there may be a laser light source 10 which produces abeam of light which may be shaped by a ball lens 20 and then throughFaraday rotator 30. The beam of light then impinges on a turning surface50 which redirects the light in a direction normal to the substrate,shown upward in FIG. 2. The light may pass through the lid substrate 60which may encapsulate the aforementioned devices disposed on the devicesubstrate 70. In FIG. 2, the turning surface is a turning mirror 50,which is a discrete structure, encapsulated in the device cavity alongwith the other components.

Suitable materials for the device substrate 70 and lid substrate 60 maybe a metal or semiconductor such as silicon, or a ceramic or glass. Thedevice cavity 65 may be etched into the lid wafer 60 using, for example,deep reactive ion etching (DRIE). The depth of the device cavity may beseveral hundred microns and have sufficient lateral extent to easilycover the components shown in FIGS. 2-8. Accordingly, the aforementionedcomponents, including turning mirror 50, rotator 30, lens 20 and lightsource 10 may be disposed in the device cavity 65, such that the devicecavity 65 encloses and encompasses the optical apparatus 110.

The laser 10 may be a light emitting laser diode for example, that canbe driven by power and signal lines which are delivered to the laser 10by one or more through silicon vias (TSVs) 40. These vias 40 are formedthrough the thickness of the device wafer 70. A number of referencesdescribe methods for making such through wafer vias 40. In theembodiment shown in FIG. 2, a discrete turning mirror 50 directs thebeam of light from the laser 10, ball lens 20 and Faraday rotator 30 toa direction normal to the substrates. The beam of light may exit throughthe lid substrate 60.

This embodiment may make use of, for example, a single mode, distributedfeedback (DFB) edge-emitting laser located within the device cavity, andthereby protected from the environment and moisture by a substantiallyhermetic seal. The single mode, edge emitting diode may be capable ofhigher data rates than a multimode vertical cavity surface emittinglasers (VCSELs), such that this embodiment may have both performance andcost advantages. The DFB laser may be modulated directly by a signal orwaveform fed to the DFB laser through the through silicon via, or it maybe driven by a direct current (DC) electrical signal applied to the TSV.However, it should be understood that the light source 10 may be atleast one of a light emitting diode, a laser diode, an edge emittinglaser diode, a laser diode, and a vertical cavity surface emittinglaser. The electrical access to the TSV 40 may be provided by a bondingpad 80, to which macroscopic electrical connections may be made. In theembodiments shown in FIG. 2, because the light is emitted through thelid substrate and thus on the obverse side compared to the electricalconnections, this embodiment may be particularly convenient for couplingto a printed circuit board or thin film circuit.

FIG. 3 shows another embodiment of the MEMS silicon optical apparatus.This second embodiment is similar to that shown in FIG. 2, except thatin this embodiment, there is also a driver 15 that drives the laser 10with a particular pattern or modulation that may represent data to becommunicated over the optical link Like the previous embodiment, thereis once again a laser light source 10, which produces a beam of lightwhich may be shaped by a ball lens 20, and then rotated by a Faradayrotator 30. The beam of light then impinges on a turning surface 50which redirects the light in a direction normal to the substrate, shownas upward in FIG. 4. The light may pass through the lid substrate 60which encapsulates the aforementioned devices disposed on the devicesubstrate 70. In FIG. 3, the turning surface is a turning mirror 50,which is a discrete structure, encapsulated in the device cavity alongwith the other components. As in the previous embodiment, the laser isdriven by through substrate vias 40, which may improve the highfrequency characteristics of the device. The electrical access to theTSV may be provided by a bonding pad 80, to which macroscopic electricalconnections may be made. In the embodiments shown in FIG. 3, because thelight is emitted through the lid substrate and thus on the obverse sidecompared to the electrical connections, this embodiment may beparticularly convenient for coupling to a printed circuit board or thinfilm circuit. In the embodiment shown in FIG. 3, the TSVs may conduct adirect current (DC) signal to the driver 15, which then modulates thesignal to encode information thereon. Accordingly, this embodiment mayinclude the power driver inside the substantially hermetic package, andthe close proximity of the compact device cavity provides for reducedpower consumption. Therefore, the microfabricated optical apparatus mayfurther comprise a device which modulates at least one of a frequencyand an amplitude, to encode the optical radiation emitted from the lightsource with an information signal.

Otherwise, the embodiment shown in FIG. 3 may be similar to that shownin FIG. 2, and the turning mirror 50 may direct the optical radiation toexit the device cavity through a roof of the lid wafer, in asubstantially parallel direction relative to the through silicon via.

FIG. 4 shows a third embodiment, wherein the turning mirror 50 directsthe beam of light downward through the device substrate 70 rather thanupward through the lid wafer 60. As in the previous embodiments, thelaser may be driven by through substrate vias 40, which may improve thehigh frequency characteristics of the device. The output of thisembodiment may be generally downward on the same side of the device asthe electrical connections are made. Accordingly, in contrast to theembodiment shown in FIGS. 2 and 3, the optical apparatus in FIG. 4 has aturning mirror 50 which may bend the optical radiation to exit thedevice cavity through the device substrate 70, in a substantiallyparallel direction relative to the through silicon via.

FIG. 5 shows a fourth embodiment of the MEMS silicon optical apparatus,wherein the turning surface 50′ is formed by a reflective surface on thelid wafer. This surface may be formed by anisotropic etching, followedby the deposition of a reflective coating on the lid wafer 60 surface.The reflective surface may be a thin film of gold (Au) or silver (Ag) orit may be a multilayer film with layer thicknesses designed to enhancereflectivity of the particular wavelength.

As in the previous embodiments, there is once again a laser light source10, which produces a beam of light which may be shaped by a ball lens20, and then rotated by a Faraday rotator 30. The beam of light thenimpinges on a turning surface 50′ which redirects the light through thesubstrate, shown as generally downward in FIG. 5. The light may passthrough the device substrate 70 on which the aforementioned devices arefabricated, in a non-normal (with respect to the substrate). As in theprevious embodiments, the laser may be driven by through substrate vias40, which may improve the high frequency characteristics of the device.The device may have the advantage of simpler fabrication. Accordingly,in some embodiments, the microfabricated optical apparatus may generateoptical radiation which exits the device cavity 65 through a sidewall ofthe device cavity 65 in the lid wafer 60, at an angle with respect tothe through silicon via. In this case, the turning surface may be areflective film deposited on a sidewall of the device cavity, whereinthe sidewall is inclined with respect to a surface of the substrate byabout 50 to 60 degrees. The turning surface may be a reflective filmdeposited on an inclined surface of an optical element located withinthe device cavity.

FIG. 6 shows a fifth embodiment of the MEMS silicon optical apparatus,wherein a laser 10 generates a beam of light which is redirected upwardby turning mirror 50. This turning mirror 50 directs the light upwardthrough the lid substrate 60. A feature lens 20′, may be formed on lidsubstrate 60 which can shape the beam of light as it passestherethrough. This embodiment is shown lacking some of the componentsdescribed previously with other embodiments, such as the ball lens,Faraday rotator or isolator, and driver. It should be understood thatthese additional components may optionally be supplied with thisembodiment as well. In FIG. 6, a horizontal line at the base of the lens20′ may suggest that lens 20′ is a separate, distinct element. It shouldbe understood that this horizontal line may be an artifact of therendering of the illustration, and that lens 20′ may be formed from amonolithic piece of silicon as described below.

The feature lens 20′ may be formed using grey scale lithography, whichmakes use of a thick photoresist. “Thick resists” means, that the resistfilm thickness is much higher than the penetration depth of the exposurelight. For standard positive resists and standard exposure wavelengths(g-, h-, i-line), this means a thickness of >5 μm. (Of course, if smallwavelengths with a very low penetration depth such as 310 nm are used,even a 1 μm resist film will be “thick” in this context). Under theseconditions, the resist film cannot be completely exposed towards thesubstrate. However, the resist may be bleached in the process asfollows: In the beginning of the exposure, light only penetrates theupper 1-2 μm of the resist film. This part of the resist film bleaches,so with the exposure going on, light will be able to penetrate the first2-3 μm of the film, and so on. As a consequence, the exposed (anddevelopable) resist film thickness goes approx. linear with the exposuredose. The transition exposed/unexposed is sufficiently sharp forreproducible greyscale lithography applications.

When the grayscale exposed resist is used in an etching process such asthe one used to make lens 20′, the thin areas of the grayscale resistare removed early on, leading to relatively deeply etched features. Thethicker areas of resist persist through the etching step, leading toshallowly etch features. Accordingly, the dome-shaped lens 20′ isproduced by having thin portions of the grayscale resist cover thehorizontal surface of the substrate, and the thickest areas over the topof the dome of the lens 20′

Grayscale lithography may be used to form a lens 20′ on either the outersurface or the inner surface of the roof of the device cavity lidsubstrate. A lens 20′ is shown on the outer surface in FIG. 7.Accordingly, the microfabricated optical apparatus may include a beamshaping element which is a lens formed in a roof of the device cavity.

As in the previous embodiments, there is once again a laser light source10, which produces a beam of light which may be shaped by a ball lens20, and then rotated by a Faraday rotator 30. The beam of light thenimpinges on a turning surface 50 which redirects the light in adirection normal to the substrate, shown as upward in FIG. 6 anddownward in FIG. 4. The light may pass through the lid substrate 60which may encapsulate the devices disposed on device substrate 60. As inthe previous embodiments, the laser may be driven by through substratevias 40, which may improve the high frequency characteristics of thedevice. The embodiment shown in FIG. 6 is shown lacking some of thecomponents described previously with other embodiments, such as the balllens, Faraday rotator or isolator, and driver. It should be understoodthat these additional components may optionally be supplied with thisembodiment as well. The lens 20′ may serve to shape, focus or collimatethe light emitted from light source 10 as driven through the throughsilicon via (TSV).

FIG. 7 shows a sixth embodiment of the MEMS optical apparatus, wherein aplurality of lasers 10 each generate a beam of light which is redirectedby turning mirrors 50. These turning mirrors 50 may direct the light inthe same or different directions as the other light sources. One or morefeature lenses 20″, may be formed on lid substrate 60 which can shapethe beams of light as they pass through. This embodiment is shownlacking some of the components described previously with otherembodiments, such as the ball lens, Faraday rotator or isolator, anddriver. It should be understood that these additional components mayoptionally be supplied with this embodiment as well. As shown in FIG. 7,the methods described here may be capable of manufacturingmicrofabricated optical apparatuses, wherein a plurality of lightsources may be disposed in a single, compact, device cavity, along withthe associated components.

The through silicon vias (TSVs) 40 which are shown in each of FIGS. 2-7may be made by a number of techniques. In one approach, blind via holesare etched into the front side of a silicon substrate, but not extendingthrough the thickness, such that material remains on the backside of thesubstrate. An insulating layer, for example, silicon dioxide SiO₂ maythen be grown on the bare silicon walls within the hole. A plating seedlayer may then be deposited conformally in the hole. A conductivematerial such as copper, may then be plated into the hole. Finally, theremaining material may be removed from the backside of the substrate toexpose the copper by, for example, grinding. The conductive copper maythereby extend through the thickness of the substrate 70. Additionaldetails as to this method of making through silicon vias may be found inco-owned U.S. Pat. No. 7,233,048, which is incorporated by reference inits entirety.

Other methods may be used to form the vias, and some may be moreappropriate for some substrate materials than others. These alternativemethods may be found in, for example, U.S. patent application Ser. No.11/482,944, U.S. Pat. No. 8,343791, U.S. patent application Ser. No.14/499,287 and U.S. patent application Ser. No. 13/987,871. Each ofthese documents in incorporated by reference in their entireties, andeach is owned by the owner of the instant invention.

The other optical components may be obtained as discrete devices, anddisposed on the fabrication substrate by pick and place machines,similar to those used in printed circuit board manufacture to placecomponents. These discrete optical elements may be held in place byepoxy or glue. The light source 10 may require a conductive bondingmaterial to maintain conductivity with the through silicon via. Thisconductive bonding material may be, for example, a relatively lowtemperature gold/tin alloy bond.

As mentioned previously, the lid substrate 60 may have a device cavity65 etched therein using, for example, deep reactive ion etching (DRIE)or anisotropic etching. Anisotropic etching tends to form sidewalls witha 56 degree slope with respect to vertical, whereas DRIE tends to makevery sharp, very vertical features. Anisotropic etching may be used onthe embodiment shown in FIG. 5, whereas DRIE may be used in theembodiments shown in FIGS. 2, 3, 4, 6 and 7. The 56 degree sidewallangle may be convenient for fabricating a reflective surface in order todirect the radiation out of the cavity.

After fabrication of the lid substrate 60 and placement of the opticalelements within the perimeter of the device cavity, the lid substrate 60may be bonded to the silicon device substrate 70. The bonding materialmay be, for example, a low temperature metal alloy bond such asgold/indium, which is formed at about 156 centigrade. Additional detailsas to methods for bonding with a gold and indium alloy may be found inU.S. Pat. No. 7,569,926, incorporated by reference in its entirety.

The embodiments illustrated in FIGS. 2-7 and described above have anumber of advantages from a manufacturing perspective. They may betested in a manufacturing environment with a conventional wafer probe tocull damaged or nonfunctional die. The design is capable of very highyield in a microfabrication production environment. They each allowintegration of multiple lasers in a single device cavity, as wasillustrated in FIG. 7.

More generally, a method for fabricating an optical apparatus on asubstrate, may include forming a device cavity in a lid wafer, forming athrough silicon via through the substrate, disposing a light sourcedriven by a waveform which generates optical radiation on the substrate,and coupling the light source electrically to the through silicon via,disposing a beam shaping element on the substrate, disposing a turningsurface which redirects the beam of light, and bonding the substrate tothe lid wafer to encapsulate the optical apparatus in a substantiallyhermetic device cavity.

The method may further include etching a blind trench into a front sideof the substrate leaving residual substrate material, coating the trenchwith an insulating material, depositing a conductive material in theblind trench, and removing the residual substrate material from abackside of the substrate to form the via. Even further, the method mayinclude bonding the substrate to the lid wafer with a low temperaturemetal alloy bond.

The method may also include forming the device cavity with anisotropicetching, leaving inclined sidewalls in the device cavity inclined atangles of about 50 to 60 degrees with respect to a surface of the lidwafer, and depositing a reflective surface onto at least one inclinedsidewall of the device cavity.

Finally, the method may include forming a lens in a roof of the devicecavity, on an inside or an outside surface.

FIG. 8 is a simplified plan view of a fabrication substrate duringprocessing in a manufacturing environment. As was described previously,the manufacturing method may be capable of fabricating a large number oflike devices on a single fabrication substrate 100. These devices mayeach be microfabricated optical apparatuses 200. This fabricationsubstrate may be bonded to a lid substrate (not shown) with cavities andperhaps other structures previously formed therein, and registered withthe optical apparatuses 200, to form a two-substrate assembly. Theindividual devices may they be singulated by sawing, dicing or grinding.

While various details have been described in conjunction with theexemplary implementations outlined above, various alternatives,modifications, variations, improvements, and/or substantial equivalents,whether known or that are or may be presently unforeseen, may becomeapparent upon reviewing the foregoing disclosure. Accordingly, theexemplary implementations set forth above, are intended to beillustrative, not limiting.

1. A microfabricated optical apparatus fabricated on a siliconsubstrate, comprising: a light source driven by a signal and disposed onthe silicon substrate, wherein the light source generates opticalradiation; wherein the signal is delivered to the light source by atleast one through silicon via (TSV) which extends through a thickness ofthe silicon substrate.
 2. The microfabricated optical apparatus of claim1, further comprising a lid wafer with a device cavity formed therein,wherein the device cavity encapsulates the optical apparatus.
 3. Themicrofabricated optical apparatus of claim 2, wherein the signal is adirect current electrical signal which is applied to the through siliconvia.
 4. The microfabricated optical apparatus of claim 1, furthercomprising: a device which modulates at least one of a frequency and anamplitude, to encode the optical radiation emitted from the light sourcewith an information signal.
 5. The microfabricated optical apparatus ofclaim 2, further comprising a Faraday rotator also disposed within thedevice cavity.
 6. The microfabricated optical apparatus of claim 1,wherein the light source is at least one of a light emitting diode, alaser diode, an edge emitting laser diode, a laser diode, and a verticalcavity surface emitting laser.
 7. The microfabricated optical apparatusof claim 2, wherein the optical radiation exits the device cavitythrough a roof of the lid wafer, in a substantially parallel directionrelative to the through silicon via.
 8. The microfabricated opticalapparatus of claim 2, wherein the optical radiation exits the devicecavity through the substrate, in a substantially parallel directionrelative to the through silicon via.
 9. The microfabricated opticalapparatus of claim 2, wherein the optical radiation exits the devicecavity through a sidewall of the device cavity, in a directionsubstantially orthogonal to the through silicon via.
 10. Themicrofabricated optical apparatus of claim 2, wherein the device cavityencapsulates a plurality of light sources.
 11. The microfabricatedoptical apparatus of claim 2, further comprising a beam shaping a lensformed in a roof of the device cavity and from material of the lidwafer.
 12. The microfabricated optical apparatus of claim 2, furthercomprising a reflective film deposited on a sidewall of the devicecavity, wherein the sidewall is inclined with respect to a surface ofthe substrate by about 50 to 60 degrees.
 13. The microfabricated opticalapparatus of claim 1, further comprising a reflective film deposited onan inclined surface of an optical element located within the devicecavity.
 14. A method for microfabricating an optical apparatus on asilicon substrate, comprising: forming a device cavity in a lid wafer;forming a through silicon via through the silicon substrate; disposing alight source driven by a waveform which generates optical radiation onthe silicon substrate, and coupling the light source electrically to thethrough silicon via; disposing a beam shaping element on the siliconsubstrate; disposing a turning surface which redirects the beam oflight; and bonding the substrate to the lid wafer to encapsulate theoptical apparatus in a substantially hermetic device cavity.
 15. Themethod of claim 14, wherein forming the through silicon via comprises:etching a blind trench into a front side of the substrate leavingresidual substrate material; coating the trench with an insulatingmaterial; depositing a conductive material in the blind trench; andremoving the residual substrate material from a backside of thesubstrate to form the via.
 16. The method of claim 14, wherein bondingthe silicon substrate to the lid wafer comprises bonding the siliconsubstrate to the lid wafer with a low temperature metal alloy bond. 17.The method of claim 14, further comprising: forming a lens in a roof ofthe device cavity, on an outside surface.
 18. The method of claim 14,further comprising: forming a lens in a roof of the device cavity, on aninside surface.
 19. The method of claim 14, wherein forming the devicecavity comprises forming the device cavity with anisotropic etching,leaving inclined sidewalls in the device cavity inclined at angles ofabout 50 to 60 degrees with respect to a surface of the lid wafer. 20.The method of claim 19, further comprising: depositing a reflectivesurface onto at least one inclined sidewall of the device cavity.